So they often cruise right below redline with enough power available to exceed either the IAS, TAS or Mmo limit.
Yeah, I know that feeling in my Cessna… 
Mark 1, thanks for linking to that article, its a good one. The sidebar article description of flutter on an RV4 prompted me to calculate TAS for a descent I once did in aircraft #1, which has a (low) Vne of 145 mph. I was coming home at 10,000 ft (about absolute ceiling) and needed to get on the ground fast to avoid incoming weather. I remember being surprised to feel substantially increased aileron forces, but had never calculated TAS for the descent – it was pretty close to Vne! I should’ve slipped down instead, at lower speed.
My dad had flutter issues on his homebuilt, resolved without damage by eliminating ‘minor’ free play in the controls with taper pins.
My mentor the ‘ex-everything’ pilot tells a story of being in a T-28 out of Pensacola as a young instructor after being told to go out and burn off some fuel. He decided to see how high it would go, climbed to 35,000 ft or something (above the approved ceiling anyway, no transponder on board) and then dived down at a high but normally reasonable IAS. Later he realized that was pretty dumb.
Paraphrased from some good work on MMOPA.
Funnily enough in the PA-46 Special Certification Review it was determined that the airframe’s Critical Flutter Speed was >600knots for the wings and >1000knots for the tail. So Vne for the PA-46 has nothing to do with flutter and hence is not TAS limited. Given the huge flutter margin, it was shown that Vne in the PA-46 does not vary by altitude and hence is an IAS not a TAS.
Peter I am afraid your Jetprop comments are just not based on facts. Its ceiling is FL270 actually and it was constrained by the Piston PA-46 limits. Nothing about test pilots and parachutes. Vmo can’t be greater than Vc under certification rules so given Piper had set the Mirage Vc at 170, the Vmo in the Jetprop was set at the same number and a little lower at FL270 (which the Mirage can’t get to). (and I am no Jetprop fan – but I owe them this!)
The subject of Vne on the Jetprop is an interesting one since Vne for the Jetprop is lower than the corresponding donor aircraft, the PA46 Malibu.
The Malibu POH only lists Vne, Va, and Vno limitations. For the Malibu Vne is 198 KIAS, whereas it is 172 KIAS on the Jetprop. Vno and Va speeds are the same for both aircraft, as are all the other V speeds, which makes sense given that the Jetprop is essentially a Malibu.
My understanding for the reduced Vne on the Jetprop is that the certification rules for turbine aircraft prohibit the use of the yellow arc normally found on the ASI of a piston aircraft, due to the risk of over speeding at lower altitudes.
The top of the original green arc piston ASI which denotes Vno of the piston aircraft becomes the new Vmo of the turbine version, and a much lower Vne is set.
There is no yellow arc on the Jetprop ASI, but instead a red line where Vno used to be. On more sophisticated turbines/turbofans this red line is a barber pole which is varied downwards with altitude to reduce the risk of flutter at the higher TAS speeds.
As Jason correctly points out the limitations due to flutter would apply equally to the Jetprop as it does the Malibu, so in this case a lower Vne cannot be attributed to that reason.
From practical experience the 172 KIAS Vne limitation at FL270 is not a factor, due to the circa 100 K difference between IAS and TAS at that height.
Managing the descent speed can be a handful if you take your eye off the ball, as can high power settings at altitudes below FL180, but there is an aural warning as soon as you exceed Vmo that keeps you in check. The onboard Shadin trend recorder also keeps a record of all exceedances including over speed warnings. 
On paper it may seem the lower Vne is a limiting factor, but in reality given the higher cruise levels I have rarely found it to be so. I also found it quite reassuring that I have a 26 KIAS buffer over the original Malibu Vne.
There is a good AOPA article here explaining the loss of the yellow arc on turbine aircraft.
Cheers – E
The Piper Cheyenne I used to fly had a “barber pole” pointer on the ASI, which was essentially a moving red line. It varied with altitude, and perhaps temperature, but I don’t know that for sure. I think that for fixed Vne aircraft, the margins between the placarded Vne and flutter allow enough reserve to accommodate the difference between TAS and IAS. I’ve flown to 110% of Vne in many aircraft, and never had a problem. I have had oscillations of installed equipment at lower speeds, and refused to fly faster until they were resolved, but that was the mod, not the basic aircraft.
But, I remind myself that flutter is possible in light aircraft….
Damn, that looks scary!!
My understanding for the reduced Vne on the Jetprop is that the certification rules for turbine aircraft prohibit the use of the yellow arc normally found on the ASI of a piston aircraft, due to the risk of over speeding at lower altitudes.
My point possibly still remains however which is that the Jetprop STC developer could have gone for more testing and got the Vne lifted, rather than be limited by what appears to be default FAA policy.
I have read that report about 600kt an 1000kt too but cannot believe that a PA46 airframe would stay in one piece at 600kt. The evidence of people overspeeding them (frozen pitot tubes, apparently) and crashing them makes such speed nonsensical. The limit may not be flutter but it is due to something else.
I think that for fixed Vne aircraft, the margins between the placarded Vne and flutter allow enough reserve to accommodate the difference between TAS and IAS.
That is what I was getting at, and that margin improves dramatically at lower levels.
I have never been involved in flutter calculation or testing, but for structure analyse the key speed is EAS, not TAS, not CAS.
I cannot believe the 600 kts either. I am no engineer but a rough estimate of the loads on the main spar must show that it will have disintegrated before reaching that speed …. (Malte? :-))
Yes of course at those speeds the plane would be overstressed but flutter is not the limiting factor. That was the point I am making.
